Messages in this thread Patch in this message | | | From | Akinobu Mita <> | Subject | [PATCH] bfs: fix bitmap size argument to find_first_zero_bit() | Date | Wed, 2 Mar 2011 20:36:39 +0900 |
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The usage of find_first_zero_bit() in bfs_create() is wrong for two reasons.
The bitmap size argument to find_first_zero_bit() is info->si_lasti but the correct bitmap size is info->si_lasti + 1 as info->si_lasti is the last valid index in info->si_imap bitmap.
Another problem is that it is impossible to detect that info->si_imap bitmap is full because there is an off-by-one bug in the return value check for find_first_zero_bit(). If no zero bits exist in info->si_imap, find_first_zero_bit() returns info->si_lasti. But the check can't catch it due to the off-by-one.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: "Tigran A. Aivazian" <tigran@aivazian.fsnet.co.uk> Cc: linux-fsdevel@vger.kernel.org --- fs/bfs/dir.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/fs/bfs/dir.c b/fs/bfs/dir.c index 685ecff..b14cebf 100644 --- a/fs/bfs/dir.c +++ b/fs/bfs/dir.c @@ -97,7 +97,7 @@ static int bfs_create(struct inode *dir, struct dentry *dentry, int mode, if (!inode) return -ENOSPC; mutex_lock(&info->bfs_lock); - ino = find_first_zero_bit(info->si_imap, info->si_lasti); + ino = find_first_zero_bit(info->si_imap, info->si_lasti + 1); if (ino > info->si_lasti) { mutex_unlock(&info->bfs_lock); iput(inode); -- 1.7.4
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